Correct method to analysis and design pile raft using staad.pro and staad foundation?

Dear Sir,

Need your help in clarified my method to analysis pile raft.

I model the pile raft using staad.pro and asign plate with thickness of 1.8m, for foundation, i asign as plate foundation with subgrade modulus of 150kN/m2/m which equal to 1.5kN/m2 of bearing capacity. Then I asign load to it and run for analysis.

With the analysis result I transfer it to staad foundation, i asign mat foundation and add pile to it to find the max reaction of pile and design the mat foundation.

The question is, is this is the correct method or i need to put pin or fixed support instead of plate foundation in the staad model before i transfer it to staad foundation?

Thanks